The present invention relates to a card connector for connecting an IC card to electronic devices, such as cellular phones, telephones, PDAs (personal digital assistants), portable audio devices and cameras, and more specifically to a switch structure for detecting the position of a write protect button of the IC card and the presence or absence of the IC card.
In electronic devices such as cellular phones, telephones, PDAs and digital cameras, a variety of functions are added by inserting an IC card with a built-in memory or control IC, such as a SIM (subscriber identity module) card, an MMC (multimedia card), a Smart Media (tradename) card and an SD (super density or secure digital) card.
In a connector structure for removably accommodating such an IC card, a plurality of contact terminals made of a metal leaf spring are provided in a connector housing to make contact with a plurality of contact pads formed on the front or back surface of the inserted IC card to electrically connect the IC card to the electronic device having that connector. The contact pads of the IC card include a power supply pad connected to a power supply line and a plurality of signal pads for transferring various signals. These contact pads are connected via the contact terminals of the card connector to a power supply circuit and various signal processing circuits in the electronic device.
The IC card of this kind normally employs some means for prohibiting the write operation in order to protect information stored in its internal memory. One such means is a write protect button that can slide between two positions, as in a floppy disk. In such a slide button system, the card is provided with a write protect button that can slide between two positions and which, when it is situated at one position, sets the card to a write disable state and, when it is slid to the other position, sets it to a write enable state. On the connector side, a detector needs to be provided that detects the slide position of the write protect button.
Further, in addition to the slide position signal of the write protect button, the electronic device often calls for a signal indicating whether the card is inserted or not. Hence, the connector should also be provided with a detector for checking the card insertion.
As a sensor structure for detecting a variety of these states, a light-based sensor structure may be considered. The light-based sensor structure, however, has drawbacks that a sufficient detection precision cannot be expected as the card becomes thinner and smaller and that the installation of a light sensor can hinder reductions in size and cost. Hence, a sensor into structure utilizing the engagement and disengagement of a contact leaf spring is considered the most promising structure overall.
When these detectors are to be constructed of contact leaf springs, because each detector requires a pair of contact leaf springs, the total number of contact leaf springs required in the connector as a whole is two times the number of detectors.
Such a construction therefore has a large number of parts making up the detectors and requires a large space to accommodate these parts, which is detrimental to reducing the thickness and size of the connector structure.
Further, when the detection switch for the write protect button and the card recognition switch are to be installed inside the connector, it is difficult to arrange the two switches efficiently in a small space. Thus, a layout has been called for which allows these two switches to be arranged efficiently in as small a space as possible.
The present invention has been accomplished under these circumstances. It is an object of the invention to provide a switch structure of a card connector that can efficiently arrange in a small space the switches for detecting the write protect button and for checking the presence or absence of the card.
It is also an object of the invention to provide a switch structure of a card connector which can construct the write protect detection switch and the card recognition switch, both composed of contact leaf springs, by using a small number of parts and which can arrange these switches in a small space.
Viewed from one aspect, the present invention provides a switch structure of a card connector, wherein the card connector holds a card in a connector housing in such a manner that contact pads of the card engage contact terminals arranged in the connector housing, the card having a write protect button slidable in a recess formed in a card side surface, the switch structure comprising: a first switch arranged on a side wall portion of the connector housing to detect a slide position of the write protect button; and a second switch arranged in a card abutment wall of the connector housing to detect the presence or absence of the inserted card.
With this invention, a pair of the first and second switches are collectively arranged in a part of the connector housing corresponding to a front corner of the card, thus allowing the two switches to be installed efficiently in a small space and contributing to a reduction in the size of the connector structure.
Another aspect of the present invention provides a switch structure of a card connector, wherein the first switch and the second switch have: a cantilevered first contact leaf spring urged to engage its engagement portion with a part of the recess corresponding to one slide position of the write protect button of the inserted card; a second contact leaf spring urged to engage its engagement portion with a part of the recess corresponding to the other slide position of the write protect button of the inserted card, the second contact leaf spring extending along the first contact leaf spring on the inner side of the first contact leaf spring; and a third contact leaf spring urged to engage with a front face wall of the inserted card and adapted to come into contact with the second contact leaf spring when the card is inserted; wherein the first switch detects the slide position of the write protect button according to a displacement of the first and second contact leaf springs in a direction of their engagement or disengagement and the second switch detects the presence or absence of the inserted card according to a displacement of the second and third contact leaf springs in a direction of their engagement or disengagement.
In this invention, one of the contact leaf springs making up the two switchesxe2x80x94the write protect detection switch and the card recognition switchxe2x80x94is shared by the two switches. This can reduce the number of parts of the contact leaf springs and therefore the cost and space.